Why Do We Have Police Forces?

I mean, really? The question is prompted by the riots going on in Toronto, in connection with the G-20 meeting. The same crowd of knaves and fools that always turns out for such events has descended on Toronto and has run riot through much of the city. The criminals have burned a number of vehicles (maybe some of them are from France), as shown in this photo:
Strangest of all is that the burning vehicle in the background is a police car. How does that happen? Didn’t it contain policemen? Were they unarmed? I really don’t understand the school of police work that apparently considers it good practice to stand by futilely while criminals seize your car and set it on fire.
It wasn’t just vehicles, either. Roving bands of criminals smashed windows and looted stores up and down the streets of downtown Toronto:
Again, I simply fail to understand. Are Toronto policemen not armed? Does it not concern them when rovings bands of criminals smash windows and loot stores? People who engage in public, violent crime are asking to be beaten with clubs and, if necessary, shot. I always thought that was the main reason we keep policemen on the payroll.
To be fair, the police have made some arrests. But all too often, they have been mere spectators:
I’ve spent very little time in Toronto over the years. Last time I was there, it reminded me of an American city of the 1970s–dirty, with a menacing street population and a whiff of violence in the air. That was only an impression, but it may be that inept police work didn’t start with the G-20.
At the Corner, Mark Steyn comments on “spectators in body armor.”

I may have to revise my old line about the British police being “the most monumentally useless in the developed world”. For the G20 summit, the Toronto coppers ordered up a ton of new body armor, weaponry, gas masks, etc – and then stood around in their state-of-the-art riot gear watching as a bunch of middle-class “anarchists” trashed the city. Streetcars were left abandoned, and even police cruisers were seized, vandalized and burned. …
The Toronto PD are your go-to guys if you want a fetching police escort for the Queers Against Israeli Apartheid float in the Pride Parade, but they don’t otherwise seem to perform any useful function.